That doesn't hold true for people taking beta carotene supplements. In fact, the landmark Carotene and Retinol Efficacy Trial, or CARET -- intended to verify the effectiveness of supplements in preventing cancer -- found that current and former smokers taking beta carotene supplements actually showed an increased risk of contracting the disease.
Although dietary beta carotene is relatively innocuous, the concentrated form found in supplements can have undesirable interactions with specific medications. The University of Maryland Medical Center notes that beta carotene, taken in conjunction with vitamins E and C and the mineral selenium -- all found in multivitamins -- can reduce the effectiveness of some statins.
It can also accelerate liver damage when combined with excessive alcohol consumption. These problems can keep you from getting enough vitamin A:. Women who are pregnant or breastfeeding may need to take supplements. Be sure to talk to your healthcare provider before doing this. Beta-carotene may reduce the risk of some types of cancer, such as prostate cancer. But more research is needed to know the effects of vitamin A on other types of cancer. It may reduce the risk of heart disease and stroke.
However, studies seem to show that neither beta-carotene nor vitamin A help prevent coronary heart disease. One study found a higher risk of lung cancer in smokers and workers exposed to asbestos when they had more beta-carotene. There are no Dietary Reference Intakes for beta-carotene.
The Recommended Dietary Allowances for vitamin A are noted below. This table notes the IU of vitamin A in foods. It also notes the percentage of your daily value of vitamin A that the food meets.
Eating more fruits and vegetables can help you get more beta-carotene. Red, orange, deep yellow, and dark green produce tends to be high in carotenoids. Vitamin A deficiency can cause symptoms such as, night blindness, fatigue, skin issues, and a weakened immune system. Severe vitamin A problems can lead to blindness. This is a leading cause of blindness in some parts of the world.
Chronic consumption of large doses of vitamin A can cause liver damage. It can also cause birth defects in a fetus. Later symptoms include severe headaches and general weakness. Bone and joint pain are common, especially among children. Fractures may occur easily, especially in older people.
Children may lose their appetite and not grow and develop normally. Their skin may itch. The liver and spleen may enlarge. Taking very high doses of vitamin A or isotretinoin a drug derived from vitamin A used to treat severe acne during pregnancy can cause birth defects.
Consuming very large amounts of vitamin A all at once can cause drowsiness, irritability, headache, nausea, and vomiting within hours, sometimes followed by peeling of the skin.
Pressure within the skull is increased, particularly in children, and vomiting occurs. Coma and death may occur unless vitamin A consumption is stopped. Taking isotretinoin a vitamin A derivative used to treat severe acne during pregnancy may cause birth defects.
Women who are or who may become pregnant should not consume vitamin A in amounts above the safe upper limit 3, micrograms because birth defects are a risk. The diagnosis of vitamin A toxicity is based mainly on symptoms. To confirm the diagnosis, doctors may also do blood tests to measure the level of vitamin A.
The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so. The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
If you have high blood levels of vitamin A, your body will convert less beta-carotene to vitamin A. If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule.
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